Table 1.

Rate of Synonymous Substitution and Divergence Time of PRRSV by Distance-Based Method and Maximum Likelihood Method

	Distance-Based Method	Maximum Likelihood Method
Rate of synonymous substitution	(7.7 ± 2.1) × 10−2	(4.74 ± 0.3) × 10−2
Divergence time of PRRSV	1986 ± 1.8	1973 ± 1.3